sedimentary
Weathered flint (chert) pebble
Microcrystalline quartz, SiO₂ (flint/chert)
AI-generated identification · may be incorrectThe dark gray, smooth upper portion has a waxy luster and conchoidal fracture; quartz hardness is about 7 on the Mohs scale. The tan, rough lower area appears to be a weathered cortex or attached host material; exact composition is not identifiable from the photo.
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Physical properties
The dark gray, smooth upper portion has a waxy luster and conchoidal fracture; quartz hardness is about 7 on the Mohs scale. The tan, rough lower area appears to be a weathered cortex or attached host material; exact composition is not identifiable from the photo.
Formation & geological history
Flint formed when silica precipitated and replaced material in sedimentary deposits, commonly chalk or limestone. Its geological age depends on the source bed; weathering and abrasion likely rounded this pebble.
Uses & applications
Flint has been used historically for tools and fire-starting; chert is also used as aggregate and collected as a natural specimen.
Geological facts
Flint fractures into sharp edges, making it valuable to prehistoric toolmakers.
Field identification & locations
Look for a hard, fine-grained dark interior, waxy surface, and curved conchoidal breaks; common in sedimentary regions and stream or beach gravels. The image alone cannot confirm the tan portion’s identity.
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